Phase stability of Pt nanoclusters and the effect of a (0 0 0 1) graphite surface through molecular dynamics simulation

A molecular dynamics (MD) simulation with an embedded atom scheme (EAM) is used to investigate the phase stability of Pt _n ( n = 38, 147, 309 and 561 atoms) nanoclusters under various temperature conditions. The heating and freezing behaviors show that the Pt ₁₄₇, Pt ₃₀₉ and Pt ₅₆₁ clusters have icosahedral morphologies in the temperature range of 460-660 K during freezing, where their formation energies are 0.051 eV/atom for Pt ₁₄₇, 0.056 eV/atom for Pt ₃₀₉, and 0.067 eV/atom for Pt _561. The calculation of the free energy change, which is based on the Gibbs-Thomson effect, implies that the coalescence phenomenon of the nanoclusters is a thermodynamically stable process. On a (0 0 0 1) graphite surface, the bottom layer of a Pt nanocluster is rearranged to a close-packed plane due to the arrangements of carbon atoms on the graphite surface, and this rearrangement disturbs the formation of a spherical Pt cluster.